I try to keep the companion app installers archived here: http://zubersoft.com/mobilesheets/archive/
It looks like I missed 2.4.8 but you should be able to try earlier versions that are still compatible. I'm really sorry you've run into all these issues though. I wish I knew why that was happening, but I haven't been able to reproduce any issues on my device. As a side note, remember that if the database disappears, you can easily restore it under Settings->Backup and Restore->Restore Automatic Database Backup. You don't need to restore a full backup or do anything else, as all of your song files are still in place, it's just the database that got corrupted.
It looks like I missed 2.4.8 but you should be able to try earlier versions that are still compatible. I'm really sorry you've run into all these issues though. I wish I knew why that was happening, but I haven't been able to reproduce any issues on my device. As a side note, remember that if the database disappears, you can easily restore it under Settings->Backup and Restore->Restore Automatic Database Backup. You don't need to restore a full backup or do anything else, as all of your song files are still in place, it's just the database that got corrupted.